Accelerometers are used in a variety of applications to provide an accurate indication of an acceleration force. For instance, some vehicle airbag systems which deploy an airbag under certain conditions to protect vehicle passengers, utilize accelerometers to provide an indication of acceleration placed on the vehicle. Because accurate detection of acceleration is often critical, accelerometers typically utilize self-testing mechanisms to facilitate testing of the accelerometer. Particularly important is a self-test feature which checks the mechanical integrity and stability of the accelerometer. In the micro-machined type of accelerometers which are sometimes utilized in vehicle airbag systems, conventional self-testing mechanisms introduce additional circuit elements, thereby adding additional cost and complexity to the manufacture of the accelerometer and to the subsequent diagnostic testing of the accelerometer. Moreover, conventional self-testing mechanisms can cause temperature coefficient problems, and also only test electrical continuity, rather than testing the mechanical integrity of the acclerometer.
Accordingly, there is a need for a micro-machined accelerometer which provides an improved self-testing mechanism.